Your heart is in the right place, and Stanislav Petrov deserves all of our respect. However, the reality is more complicated. Due to geography, USSR used a system called dead hand [0] to detect a nuclear attack and to retaliate. In particular, SLBMs launched by US off the coast of Norway needed only 5 minutes travel time to Moscow. Similarly, US Pershing missiles stationed in West Germany required about 6-7 minutes to reach Moscow. All of these meant USSR required a nuclear retaliatory system that could prevent hasty decisions. Hence Dead Hand system.

On the other hand, Vasily Arkhipov probably stopped a nuclear war in Oct 1962 [1]...

[0] https://en.wikipedia.org/wiki/Dead_Hand [1] https://en.wikipedia.org/wiki/Vasily_Arkhipov